Generally, a vehicle is provided with a cooling device for drawing cold air from the outside to the inside to cool heat of an internal device, for example, a radiator grill which is provided at a front side of an engine room to introduce cold air from the outside to the engine room.
In particular, in the case of large vehicles such as buses, an air pressure driving device is frequently used. In the air pressure driving device, an engine room is provided at a rear side thereof, high pressure compressed air is generated by using a compressor during driving of the engine and stored in an air tank which is provided in a separate room, and the stored compressed air is used during the braking or when the braking is required.
In the air pressure driving device, a cooling fan is provided in a room including the air tank (generally, an APU room) or the outside air is allowed to flow in the room so that the compressed air which is compressed and stored at high pressure and temperature suppresses the generation of moisture necessarily caused according to an environmental temperature, thereby reducing an absolute humidity of the compressed air.
In respects to the above-mentioned pneumatic device, the pressure is increased due to the compressor which is provided at a side of an engine and compresses air, and the temperature of the compressed air is increased to about 90° while the compressed air flows between compressor A and the air tank. Thus, generally, an air drier is provided in the pneumatic device, so that air comes into contact with a substance such as a desiccant to remove gas-phase moisture from air and discharge the moisture to the outside of the vehicle while the gas-phase moisture is converted into liquid-phase moisture.
However, the air drier may provide a fatal cause of a brake device trouble because the air drier obstructs the movement of air or blocks a pneumatic tube during the braking due to the moisture when the moisture is generated according to a change in phase of the compressed air due to a change in temperature of the air tank.
Therefore, the air drier has a structure in which an internal tube is formed to have a spiral shape so as to ensure a sufficient length and air flowing from the compressor moves while heat exchanging occurs between the air flowing from compressor A and the outside air to reduce the temperature.
In addition, with respect to the air drier, it is required that the cooling is performed so that the temperature of the room including the air drier is not increased to a predetermined value or more in order to maintain desirable moisture removing performance in the compressed air.
Accordingly, in the case of the bus, in order to maintain the desirable temperature of the room where the air drier is provided, the outside air flows into the APU room which is structured in such a way that the room is cooled in conjunction with the air drier by using a cooling fan operated by the motor or an air tank and a tube line are provided in conjunction with the air drier at a rear side of the bus to cool the APU room.
However, in the case of when the outside air flows in the APU room in the bus, the cooling performance depends on the outside air introduction performance of the grill provided in the APU room, and the outside air introduction grill is typically provided at a side of the APU room. Accordingly, the case is disadvantageous in that the outside air does not sufficiently flow in the APU room during the driving of the bus.
Furthermore, since the grill which is provided in the APU room so as to introduce the outside air into the APU room is formed to have a simple structure including channels transversely disposed at predetermined intervals, it is difficult to allow the outside air to desirably flow through the grill into the APU room.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.